Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: birt on June 21, 2010, 05:12:48 pm

Title: going nuts with EF... tubes
Post by: birt on June 21, 2010, 05:12:48 pm

i was looking at Telefunken/siemens mic preamp schematics (planning to build one some day, as i plan to build lots of things) and as it uses EF804 tubes i started looking in my collection to see if i have some. i found out the EF804 is the EF86 variant that doesn't go microphonic in a couple of hours, the E80F claims the same. hooray!

so i started looking and found.. a lot of tubes. i've kind of lost my way now. i don't want to make an exact copy of the V78 preamp. i want to make something that does more or less the same, also using pentodes.

what i found:
49x EF80
12x EF183
E80F
2x EF40
9x UF80
EF88
EF42
EF93
5x EF184
6x EF89
10x EF86
4x EF85
EF83
E83F
E180F
EF91

and now i'm lost :p
what to do? what to do? keep the EF86 and sell the rest to buy EF804's??

Title: Re: going nuts with EF... tubes
Post by: DummyLoad on June 21, 2010, 05:57:32 pm

E80F
EF40
EF86

are definite keepers.

the rest are hi mu and/or vari mu RF tubes. the EF89 looks like it might be of interest for a compressor/limiter. the EF93 are the euro eqiv. to the 6BA6 and is what manley now uses in their vari-mu compressor/limiter - basically a knock-off of a fairchild 660/670 compressor/limiter.